SAT语法求助1.Scientists (know from) the chemical coposition of A
SAT语法求助
1.Scientists (know from) the chemical coposition of Antarctic ice
(that) (there is) more carbon dioxide in the earth's atmosphere today
than (the past) 65000 years.
但是为啥啊?
2.Maria (Merian,who undertook an expedition to study) insects in Suariname in 1699,when she was fifty-two years old.
B) Merian undertook an expedition to study
E) Merian has undertaken an expedition to study
为什么是E而不是B?